Resesrch On The Algorithm Of BDS Triple-frequency Date Processing And Program Implementation

This paper starts from the background of GNSS modernization, discusses the BDS second generation system with a main line of triple-frequency data processing, analyses the related algorithm and carries out the corresponding experiments, and improves the existing problems. Thus it provides some beneficial reference for the rapid development of our country's Beidou navigation system.One of the main sign of GNSS modernization is the use of triple-frequency or multi-frequency observation data. Multi-frequency data can form more excellent combination with longer wavelengths, lower noise and week ionosphere delay, so as to provide new opportunities for the resolve of key technologies in navigation and positioning. This paper conducts the research from the following aspects:1. For the BDS triple-frequency phase combination, the paper starts from the definition of phase combination, analyses the error characteristics of combination data, chooses some global optimal combination coefficient, and puts forward a combination coefficient selection method based on planar inequality constraints.2. For the BDS triple-frequency cycle-slip detection and repairing, the paper firstly studies several single and dual frequency methods, and raises an improved Kalman filtering method. Then pseudo-range phase combination method and phase without geometric distance method is introduced, and cycle-slip detection formula is deduced. The experiments prove that above two methods are very sensitive to small cycle-slip under big sampling rate. A combination phase difference method that differs between combination phases is put forward. Experiments prove that this method can detect cycle-slip as small as 1 week. The thesis puts forward that single frequency Doppler method is extended for triple frequency which increase the use of multiple observations data. Tests results show that cycle-slip more than 10 cycles can be detected3. For the BDS triple frequency ambiguity resolution, B_Tcar method which is based on the observation range is studied. This method fixed ultra wide lane, wide lane and the original frequency ambiguity step by step. Experimental results show that ambiguity can be fixed under single epoch for short baseline. But original frequency ambiguity fluctuates in several weeks due to ionosphere correlation between stations becomes weaker for long baseline. The paper derivates TEC and ionospheric delay formula using triple frequency combination, and corrects ionospheric delay for long baseline. After correction, fluctuation range can be decreased to 1 week. Wavelet denoising method is introduced owing to the fact that original frequency ambiguity is affected by noise for middle and long baseline. And denoising effect is analyzed for different wavelet basis function. The paper proposes a noise error minimization way to calculate middle and long baseline ambiguity, and deduces the formula to minimize noise error. This method can effectively reduce the noise effect to the original frequency ambiguity fixing.4. At end of the thesis, a triple-frequency data process software based on MATLAB GUI is developed. The software implements the related principle with program, which enhance the practicability.